This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Glycosaminoglycans are polymeric carbohydrates forming an important part of the extracellular matrix. Interactions of proteins with this matrix are important in directing cell migration, modulating cell signaling and regulating the physical properties of the extracellular fluids. Structurally characterizing the interactions is essential to understanding function and developing therapeutic agents that can control those functions. This project combines NMR methodology with mass spectrometry footprinting methodology in an attempt to develop methodology that can characterize interactions ranging from those of individual proteins with small glycosaminoglycan oligomers to those of higher order protein complexes with polymeric material. The NMR methodology is based on intermolecular NOEs and chemical shift perturbation. It will eventually be extended to methods which allow structure determination of bound oligomers. The mass spectrometry methodology is based on the difference in modification of surface exposed amino acids on the protein by photolytically produced hydroxyl radicals in the presence and absence of oligomers (oxidative footprinting). Methods are being developed using a well defined chemokine (CCL5) interacting with chondroitin sulfate oligomers as a target system. Concentration gradients in extracellular CCL5 dictate the migration of T-cells to sites of injury and the binding to glycoaminoglycans appears essential to the maintenance of the concentration gradients. While a crystal structure exists, no models for the interaction of CCL5 with oligomeric materials currently exist.